Movable bushing for a pressure-loaded gear pump



' 1959 D; L. LORENZ 2,870,720

MOVABLE BUSHING FOR A PRESSURE-LOADED GEAR PUMP Filed Jan. 10, 1956 I 2Sheets-Sheet 1 :1, v9. IIIII Dozm/d L. Lorenz Jan. 27, 1959 o. I LORENZI MOVABLE BUSHING FOR A PRESSURE-LOADED GEAR PUMP Filed Jan. 10. 1956 2Sheets-Sheet 2 IZlL E Z'ZTUT Dona/a Lorenz MOVABL BUSHINCE FOR APRESSURE-LOADED G AR PUMP Application January 10, 1956, Serial No.558,307

' 3 Claims. (Cl. 103-126) This invention relates generally to pumps andmore particularly to an improved movable bushing for a pressure-loadedgear pump.

Figure 1 is a cross-sectional view of a pressure loaded gear pumpincorporating the movable bushings provided in accordance with theprinciples of the present invention;

Figure 2 is a fragmentary cross-sectional view with parts removed forthe sake of clarity showing additional details of structure as seengenerally on line IIII of Figure 1;

Figure 3 is an elevational view of the movable -bushing of the presentinvention;

Figure 4 is a cross-sectional view taken generally on line IVIV ofFigure 3;

Figure 5 is a fragmentary cross-sectional view taken generally online'V-V of Figure 3;

Figure 6 is a fragmentary cross-sectional view taken generally on lineYIVI of Figure 3;

Figure 7 is a fragmentary enlarged view showing additional details ofconstruction of the groove illustrated in Figure 3; V

Figure 8 is a rear elevational view of the bushing shown in Figure 3;and

Figure 9 is a bottom plan view of the bushing of Figure 3.

As shown on the drawings:

The principles of the present invention are illustrated in connectionwith a pump indicated generally at 10 and including a housing 11 made upof a plurality of fastened-together casing sections shaped to provide aninlet 12 and an outlet 13 on opposite sides of a pair of intersectingbores 14 and 16 together forming a pumping cavity in which is rotated arotary fluid displacement means.

In the embodiment illustrated, the rotary fluid-displacement meanscomprise a driver gear 18 having a plurality of circumferentially spacedteeth 19 meshing with a corresponding plurality of circumferentiallyspaced teeth 20 of a driven gear 21. The teeth 19 and 20 have a rootdiameter indicated at 22 and each adjoining pair of teeth provides aspace or pocket therebetween for carrying fluid from the inlet 12 to theoutlet 13 whereupon the fluid is positivelydisplaced upon intermesh ofthe teeth 19 and 20 on the discharge side of the pump.

The driver gear 18 has a gear shaft extension 23 which is journaled in abearing surface 24 formed in the housing 11. A driving member 26-issplined as at 27 to the gear shaft extension 23. The driving member 26extends outwardly of the housing 11 through a cover member 28. The usualseal and thrust assembly indicated generally at 29 is employed toprevent leakage outwardly of the pump 10. The driving member 26 has asplined portion 30 adapted to efiect a connection with a suitable sourceof power.

The driven gear 21 is also provided with a gear shaft extension 31journaled in a bearing surface 32 formed United States Patent 0 PatentedJan. 27, 1959 in the housing 11. The housing 11 also provides a radiallyextending sealing surface 33 for engaging and sealing against anadjoining side face of the driver gear 18 and the driven gear 21. v

On the opposite side of the gears 18 and 21, the housing 11 is bored andcounterbored to receive the movable bushings provided in accordance withthe principles of the present invention. One bushing is provided 37received in a bore 38 formed in the housing 11. At

the end of the tubular extension 37 is provided a radially outwardlyextending flange 39 providing a sealing front face 40 for engaging andsealing against the adjoining side face of a corresponding driver gear18 or driven gear 21 and a pressure-receiving back surface 41 which isspaced from: an adjoining wall 42 of the housing 11, thereby to formtogether with means including a portion of the housing 11 a pressurecontrol chamber 43.

An annular radially outwardly extending shoulder 44 interrupts theperipheral surface of the tubular-extension 37 adjacent the flange 39,thereby to proportionately decrease the efiective pressure-receivingarea of the pressure-receiving surface 41 towards the inlet side of thepump for balancing unequal pressure forces in the pump ing cavity. Fluidat pressure generated by the pump 10 is communicated to the pressurecontrol chamber 43 through a fluid passageway 46 extending axially orlongitudinally through the flange 39 and communicating the outlet 13 ofthe pump 10 with the pressure control chamber 43.

The housing 11 is grooved as at 47 to receive a sealing member 48 whichengages against the peripheral surface of the shoulder 44 eccentricallyoffset towards the inlet side of the pump. Accordingly, the diameters ofthe tubular extension 37 and the flange 39 remain concentric as do thecorresponding diameters of the bore 38 receiving the tubular extension37 and a bore 49 receiving the flange 39. Any manufacturing tolerancesin connection with the eccentricity of the shoulder 44 are accommodatedby the sealing member 48.

To initially load the movable bushings 36 into sealing engagement withthe corresponding gears, the pressurereceiving back surface 41 isprovided with a plurality of circumferentially sp'zced recesses 50 eachbottoming a coil spring 51 and engaged against the wall 42 for exertinga continuous biasing force on. the movable bushing 36 in the directionof the adjoining gear side face.

The pressure-receiving surface 41 of the bushing 36 is alsocharacterized by the formation therein of a plurality of lighteningrecesses 55, thereby to decrease the overall weight of the bushingconstructiom Each bushing 36 has formed therein a bore forming a bearingsurface 52 for journaling a gear shaft extension indicated at 53 on the.driver gear 18 and at 54 on the driven gear 21.

In pumping fluid, the load which is imposed upon the gears 18 and 21 istransmitted to aportion of the assembly corresponding to the center of abeam support. Accordingly, the stress concentrations which are presentin the pump 10 produce a deflection of the beam. Additionally, there maybe some tendency to a slight misalignment in end-to-end direction. Thebearing surfaces which are provided at 52, 53 and at 52, 54 are providedwith a taper in the direction of the adjoining gear side face, therebyproviding a gradually increasing clearance space along the length of thegear shaft extensions of the corresponding gears 18 and 21. There isthus provide-d a clearance space which is generally annular inconfiguration and somewhat conical, having its widest opening at theinner portion of the support. By virtue of such provision, loadconcentration is reduced at the inner portion of the supporting memberand the clearance space thus provided facilitates the introduction ofcoolant and lubricant into the journal surface and greatly facilitatesthe dissipation of thermal energy.

In accordance with the principles of the present invention, the bearingsurface 52 terminates at the sealing front surface 40 in a chamferedrecess 56 which is formed at such a relatively sharp angle of taperrelative to-the angle of taper of the bearing surface 52 or theadjoining surfaces on the gear shaft extensions 53 and 54 as tocompletely remove bearing load on the bushing 36 immediately adjacentthe sealing front surface 40.

Means are provided to communicate the chamfered re-- cess 56 inpressure-flow relation with the outlet 13 of the pump 10, thereby tosupply at increased pressure for cooling and lubricating the bearingsurface 52. In the form of the invention illustrated, the sealing frontface 40 has formed therein a trapping relief recess 57 opposite theadjoining gear teeth 19 and 20 of the driverand driven gears 18 and 21,respectively, and on the discharge side of the bushing 36. The trappingrelief 57 prevents fluid from becoming trapped at the area of intermeshand is subject to full outlet pressure. As is clearly illustrated inFigures and 3, a drilled passageway 58 intersecting the trapping reliefrecess 57 and the chamfered recess 56 communicates fluid at outletpressure to the chamfered recess 56, thereby supplying coolant andlubricant to the bearing surface 52.

To further assist in flooding the bearing surface 52 with coolant andlubricant, a longitudinal groove 59 is formed in the bearing surface 52and extends inwardly from the chamfered recess 56 terminating as at 60short of the end of bearing surface 52.

The shape of the recess 59 is more specifically illustrated in theenlarged sectional view of Figure 7. It will be noted that the groove 59is generally semicylindrical in configuration when viewed incross-section and is particularly characterized, according to theprinciples of the present invention, by a tapered trailing edge 61 whichtogether with an adjoining surface of a gear shaft extension 53 or 54forms a convergent throat 62 converging in the direction of relativerotation between the adjoining bearing surfaces. -It is well known thatlubrication of a bearing surface journaling a relatively rotatablemember is ef fected by the formation of a fluid film between thesurfaces. Thus, the groove 59 operates as a reservoir and the convergentthroat 62 functions to carry a supply of fluid from the reservoir intothe fluid film formed between the adjoining relatively rotatablesurfaces.

in operation, the sealing front surface 40 engages the adjoining sideface of a corresponding gear and seals the fluid in the spaces betweenthe gear teeth 19 and so that the fluid being pumped will be carried bythe spaces or pockets from the inlet 12 to the outlet 13. The sealingsurface 40, however, extends radially inwardly a considerable distancebeyond the root diameter 22 of the gears 18 and 21 and, accordinglythere is a direct metal-tometal contact between the surface 40 and theadjoining gear side face. 7

In accordance with the-principles of the present invention, the frontsealing surface 40 is particularly charactcrizcd by the formationtherein of a circumferentially extending continuous annular groove 63which is located radially outwardly of the chamfered recess 56 butradially inwardly of the root diameter 22 of the gear teeth 19 and 20.The groove 63 is placed in pressure communication with the outlet 13 ofthe pump 10 by means of a drill as a buffer to'prevent binding andseizure between the gears and the bushings but also materially assistsin heat dissipation.

The sealing surface 40 is further characterized by the formation thereinof a filling recess 66 which is located outwardly of the root diameterof the gear teeth and opposite the gear teeth to assist in filling thespaces between the gear teeth with fluid at inlet pressure.

According to the principles of the present invention, the sealingsurface 40 is further characterized by the provision of a chamferedperipheral edge indicated at 68 on the outer peripheral edge of thebushing 36, as indicated in Figure 3, thereby to form acircumferentially extending passageway which communicates the outlet ofthe pump with the spaces between the gear teeth and which extendsthrough approximately through on eachbushing 36, thereby terminatingshort of the inlet side of the bushing 36. The passageway formed by thechamfered edge 68 communicates the spaces between the gear teeth andtends to even out the distribution of pressure load acting on eachbushing 36.

Each flange 39 of each bushing 36 is generally circular, however, aflattened chordal portion 70 is provided so that a pair of bushings, asshown in Figure 2 abut one another at the chordal sections 70, 70. A pinrecess 71 is formed as indicated at 71 by means of which a pair ofadjacent bushings 36 are locked against relative displacement whenassembled in a pump.

Although various minor structural modifications might be suggested bythose versed in the art, it should be understood that I wish to embodywithin the scope of the patent warranted hereon all such modificationsas reasonably and properly come within the scope of my contribution tothe art.

I claim as my invention:

1. In a high pressure gear pump, a housing having an inlet and an outletand providing a pumping cavity, and end plate means for said cavity insaid housing, said end plate means having a pressure-receiving backsurface forming together with means including a portion of said housinga pressure-control chamber, said end plate means having apressure-sealing front surface for engaging an adjoining side face of arotary gear fluid displacement means, and means placing said pressurecontrol chamber in pressure communication with said outlet, said sealingfront surface having a chamfered peripheral edge forming a passagewayextending from the outlet side of said end plate means around theperiphery and terminating short of the inlet side of said end platemeans to intercommunicate the spaces between the gear teeth and the pumpoutlet.

2. In a high pressure gear pump, a housing having an inlet and an outletand providing a pumping cavity, and end plate means for said cavity insaid housing having a pressure-sealing front surface for engaging anadjoining side face of a rotary gear fluid displacement means, the outerperipheral edge of said front surface being chamfered to form acircumferential passage extending from said outlet and terminating shortof said inlet thereby to pressure-communicate the outlet with the spacesbetween the gear teeth adjacent said circum formed in said bearingsurface of said bushing forming diverging clearance spaces extendingtowards the impeller to reduce center load concentration, said taperterminating in a chamfered recess adjacent said impeller to removelocally bearing load on said bearing surface and means communicat'mgfluid at pressure generated by the pump to said chamfercd recess forflooding the bearing surface with coolant and lubricant, said bearingsurface having a longitudinal groove extending inwardly from saidchamfered recess, said groove being particularly characterized by theformation therein ,of a

chamfered edge to provide a tapered lead-in throat converging in thedirection of relative rotation of the adjoining surfaces for assistingthe introduction of fluid into the film between the adjoining journalingsurfaces.

References Cited in the file of this patent UNITED STATES PATENTS1,254,909 Howe Jan. 29, 1918 1,271,970 Wood July 9, 1918 1,372,576Tullmann Mar. 22, 1921 1,550,099 Sayre Aug. 18, 1925 1,641,486 HeilSept. 6, 1927 6 Whaley Dec. 1, McIntyre Sept. 4, Howarth Sept. 21,Burghauser Mar. 22, Dickson Apr. 21, Heckert May 5, Marco June 15,Straub Mar. 14, Pugh Dec. 18, Taylor Dec. 20, Ilyin Jan. 6, Lauck Jan.12, Lauck Apr. 27, Orr July 6, Minshall et al. Sept. 27, .Booth et a1.Feb. 21,

FOREIGN PATENTS Austria Sept. 10, Switzerland July 16, Italy Mar. 12,Great Britain Jan. 6, France Aug. 26,

. Germany Mar. 3,

